Fast growth of magnetic fields in galaxy clusters: a self-accelerating dynamo
We propose a model of magnetic-field growth in galaxy clusters whereby the field is amplified by a factor of about 10^8 over a cosmologically short time of ~10^8 yr. Our model is based on the idea that the viscosity of the intracluster medium during the field-amplification epoch is determined not by...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
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2005
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| _version_ | 1826302344573222912 |
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| author | Schekochihin, A Cowley, S |
| author_facet | Schekochihin, A Cowley, S |
| author_sort | Schekochihin, A |
| collection | OXFORD |
| description | We propose a model of magnetic-field growth in galaxy clusters whereby the field is amplified by a factor of about 10^8 over a cosmologically short time of ~10^8 yr. Our model is based on the idea that the viscosity of the intracluster medium during the field-amplification epoch is determined not by particle collisions but by plasma microinstabilities: these give rise to small-scale fluctuations, which scatter particles, increasing their effective collision rate and, therefore, the effective Reynolds number. This gives rise to a bootstrap effect as the growth of the field triggers the instabilities which increase the Reynolds number which, in turn, accelerates the growth of the field. The growth is explosive and the result is that the observed field strength is reached over a fraction of the cluster lifetime independent of the exact strength of the seed field (which only needs to be above ~10^{-15} G to trigger the explosive growth). |
| first_indexed | 2024-03-07T05:46:08Z |
| format | Journal article |
| id | oxford-uuid:e74a74ef-9b6a-4a9e-96c3-9658d17e0aec |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:46:08Z |
| publishDate | 2005 |
| record_format | dspace |
| spelling | oxford-uuid:e74a74ef-9b6a-4a9e-96c3-9658d17e0aec2022-03-27T10:37:26ZFast growth of magnetic fields in galaxy clusters: a self-accelerating dynamoJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:e74a74ef-9b6a-4a9e-96c3-9658d17e0aecEnglishSymplectic Elements at Oxford2005Schekochihin, ACowley, SWe propose a model of magnetic-field growth in galaxy clusters whereby the field is amplified by a factor of about 10^8 over a cosmologically short time of ~10^8 yr. Our model is based on the idea that the viscosity of the intracluster medium during the field-amplification epoch is determined not by particle collisions but by plasma microinstabilities: these give rise to small-scale fluctuations, which scatter particles, increasing their effective collision rate and, therefore, the effective Reynolds number. This gives rise to a bootstrap effect as the growth of the field triggers the instabilities which increase the Reynolds number which, in turn, accelerates the growth of the field. The growth is explosive and the result is that the observed field strength is reached over a fraction of the cluster lifetime independent of the exact strength of the seed field (which only needs to be above ~10^{-15} G to trigger the explosive growth). |
| spellingShingle | Schekochihin, A Cowley, S Fast growth of magnetic fields in galaxy clusters: a self-accelerating dynamo |
| title | Fast growth of magnetic fields in galaxy clusters: a self-accelerating
dynamo |
| title_full | Fast growth of magnetic fields in galaxy clusters: a self-accelerating
dynamo |
| title_fullStr | Fast growth of magnetic fields in galaxy clusters: a self-accelerating
dynamo |
| title_full_unstemmed | Fast growth of magnetic fields in galaxy clusters: a self-accelerating
dynamo |
| title_short | Fast growth of magnetic fields in galaxy clusters: a self-accelerating
dynamo |
| title_sort | fast growth of magnetic fields in galaxy clusters a self accelerating dynamo |
| work_keys_str_mv | AT schekochihina fastgrowthofmagneticfieldsingalaxyclustersaselfacceleratingdynamo AT cowleys fastgrowthofmagneticfieldsingalaxyclustersaselfacceleratingdynamo |